This unit is designed to meet the California Science Content
Standards for third through seventh grade. The lessons in this
unit can be adapted for each of the these grade levels. The reading
level of some of the links is more appropriate for grades 5-7.
It would be wise to preview the material on each link before
making assignments. Teacher discretion should be used when adapting
these activities to a particular grade level. Each lesson is
designed to be used as in independent activity or as part of
an integrated long term unit. Activity 4 contains links to some
optional online activities>

See this chart for grade
level appropriateness and other information and hints:

Students will need litmus paper, dissolved oxygen tablets,
nitrate test paper, a sechi disk (can be made with a button and
string), and other materials described in online experiments
such as jars, thermometers, etc.